That's so weird, i use translate.google.com to help sometimes and nosotros son ninos translates to we are children as well as nosotros somos ninos. Must be a poor translation on their part! Because further googling confirms that somos = we and son = they... >_<!
OK but can you really say "Nosotros somos nino" as if the singular form of 'nino' can coast on the plural signifiers of the nosotros forms that precede it? I failed to mark this correct and got the question wrong. Really?